The present invention relates to wet shaving systems of the blade type and more particularly to a shaving system having one or more blades positioned within a blade cartridge and having cutting edges protected by guard ribs.
Shavers have long sought a wet shaving system that provides a smooth and comfortable shave without causing annoying cuts and abrasions on the skin of the shaver. In many instances the blade being at the wrong blade exposure or an improper shaving angle causes cuts and abrasions.
The terms xe2x80x9cblade exposurexe2x80x9d and xe2x80x9cshaving anglexe2x80x9d represent geometrical relationships between the blade and the shaving surface. These terms as well as another term commonly used in the art are defined as follows. First, the term xe2x80x9cshaving planexe2x80x9d means the plane tangent to skin engaging surfaces, referred to as a guard and a cap, which are disposed on both sides of the blade so as to engage the shaving surface before and after engagement by the blade. Second, the term xe2x80x9cblade exposurexe2x80x9d means the distance by which the blade edge projects forward of the shaving plane. Third, the term xe2x80x9cshaving anglexe2x80x9d means the acute angle between a plane tangent to the cutting edge of the blade and the shaving plane.
Various approaches have been used in an effort to present a blade cartridge having the correct blade exposure and shaving angle. One approach disclosed in related art patents includes the configuration of a blade cartridge having blades that are movably mounted therein such that when force is applied to the blades they move to a less aggressive blade exposure and shaving angle. A second approach is to pivotally mount the blade cartridge to a handle that allows the entire cartridge to rotate in response to shaving forces to a less aggressive blade exposure and shaving angle.
A third approach involves constructing a blade cartridge wherein the blade assembly, including the blades, a spacer, and a cap member, are movable as a unit between various blade exposures and shaving angles within various degrees of control and direction in response to forces encountered during shaving. For example, Ciaffone et al., U.S. Pat. No. 4,461,079, describes a razor cartridge comprising a body portion 10 which includes a guard bar 12 (FIGS. 1-5). The guard bar 12 defines a leading skin-engaging surface fixed to the body portion. Rear beam 17 spans end walls 14 and 16 of the body portion 10 and a medial support member 13 to join the front of the cartridge 12 to the end thereof. A plurality of generally flat coplanar segments 18, 19, 21, and 22, each having an opening 23, are hinged to the rear beam 17 by mating webs 24, 26, 27, and 28 (col. 2, lines 50-52). Collectively, the segments 18, 19, 21, and 22 define a blade seat which is operable to pivot about the beam 17, thereby changing the attitude of blade edge relative to guard bar 12 (col. 2, lines 53-57). A cap 33 is apparently placed above an assembly of two skin-engaging blades 34 and 36 straddling a spacer 37 (FIG. 3). The two blades and the spacer are secured to one coplanar segment 21 of the blade support or blade seat by a conventional rivet 38 to form a rigid unit. A hinge 27 connects the coplanar segment 21 to the rear-beam 17 (col. 3, lines 1-8). As compared to the position of the blade edges relative to the guard bar at the normal or free position set in accordance with a predetermined blade geometry (FIG. 3), a change in blade geometry occurs during the course of shaving when a shaving force F causes the blade package to rotate or pivot about rear-beam 17 in the direction of arrow R where the blade edges are rendered less xe2x80x9caggressivexe2x80x9d (FIG. 4, col. 3, lines 13-23). Upon relaxation of shaving forces, the elastic memory of hinges 24, 26, 27, and 28 forces the blade seat, and therefore the blade edges, to return to their normal position (FIG. 3., col. 3, lines 24-26).
Other approaches include foil guarded cartridges, taped blades and wire wrapped blades or cartridges. Foil guarded cartridges are typically constructed with a piece of foil extending over the cap member, the blades and the platform member. The foil has openings adjacent the blade edges to allow the blade edge to contact the skin of the shaver. Taped blades include a piece of material extending from the upper surface of the blade over the blade edge to the lower surface of the blade. The material has openings positioned along the blade edge to allow the blade edge to contact the skin of the shaver. Wire wrapped blades include a piece of wire extending around the entire blade and over the blade edge. Alternatively, the piece of wire can be wrapped around the entire blade assembly and over the blade edges, to form a wire wrapped blade cartridge.
The various approaches discussed above present several different problems. First, the cost of manufacturing these blade cartridges is high. The relatively complex mechanisms used to produce blade cartridges having movable blades or movable blade assemblies significantly increases the cost to produce and assemble such blade cartridges. Similarly, wire wrapped, foil guarded and taped blades are difficult and expensive to assemble adding cost to the finished product.
A second problem with the movable blade cartridges described above is the delicate, and sometimes unpredictable, nature of the movable blades. By movably mounting a blade within a blade cartridge, the risk arises that the blade may move to a more aggressive blade exposure or shaving angle, thereby cutting the shaver. Additionally, by movably mounting a blade within a blade cartridge, the risk arises that the movable connection may fail and the blade may become dislodged from the blade cartridge.
A second problem with the wire wrapped, foil guarded, and taped blade approaches is that they tend to grab and pull whiskers that become caught between the protective member and the blade. They also tend to collect debris and are hard to flush clean. The foil guarded, taped blade, and wire wrapped cartridges are limited in how close of a shave they can produce by the thickness of the foil, tape, or wire (diameter) used to cover the blades. The wire wrapped blades have the disadvantage that the wire tends to embed itself into the blade thereby damaging the blade. Additionally, the wires are easily disturbed thereby effecting shaving characteristics of the blade and potentially causing wear on the blade edge.
Consequently, a need exists for a blade cartridge incorporating an effective means for preventing cuts and abrasions caused by a razor blade being repeatedly passed over the skin of a shaver. The blade cartridge should be constructed to provide proper blade exposure and shaving angle, while still providing a close shave. The blade cartridge should also be cost effective to manufacture and durable. In addition, the blade cartridge should be configured to effectively shave varying contours and surfaces.
The blade cartridge of the present invention has one or more protruding members, or guard ribs, positioned proximate the skin engaging edges of the blades such that a portion of the blade adjacent the guard ribs has a negative exposure. The guard ribs provide an effective means for preventing cuts and abrasions caused by a razor blade being repeatedly passed over the skin of a shaver. The guard ribs provide the portions of the skin engaging edges with a negative blade exposure that prevents overexposure of the blades to the skin, while allowing the remainder of the skin engaging edges of the blade to still provide a close shave. The blade cartridge is cost effective to manufacture and durable, in that the present invention provides a simple arrangement without moving parts. In addition, the blade cartridge is configured to provide an effective shave on a variety of contours and surfaces. The plurality of guard ribs on the guard, spacer and cap define a blade exposure at a shaving plane at a tip of said guard ribs from between about xe2x88x920.762 mm to xe2x88x921.5 mm, and a blade exposure at a trough from between about +0.508 mm to about +1.270 mm.
Preferably, the blade cartridge is connected to a handle, and can be detachably connected so as to allow the blade cartridge to be replaced when it becomes worn. Alternatively, the blade cartridge may be permanently mounted on or integrally attached to a handle in the form of a disposable razor.
The present invention further includes one or more protruding members, or guard ribs, evenly positioned along the blade cartridge. The guard ribs preferably each have an arcuate contact surface and are narrow in thickness in a direction along the skin engaging edge. In addition to the guard ribs on the platform member, the present invention preferably further includes protruding members, or guard ribs, on the cap member. The guard ribs on the platform member are preferably aligned with and substantially continuous with the guard ribs on the cap member.
In a further embodiment, the blade cartridge includes a secondary blade and a spacer separating the primary blade and the secondary blade. In this embodiment the spacer preferably has protruding members, or guard ribs, positioned proximate the skin engaging edges of the primary and secondary blades. In this embodiment the spacer preferably has an open portion abutting the aperture in the primary blade that allows debris to flow through the resulting flow path and out the bottom of the blade cartridge. As with previous embodiments, the guard ribs on the spacer are preferably aligned with and substantially continuous with the guard ribs on the cap member and the platform member. Similarly, additional spacers with protruding members and additional blades may be added to the blade cartridge to produce further embodiments.